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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cf74c425462bb691c499195d65a45f3ae56250694bb3c2b301e459349797db8' 
  AND token = 'X7yIIBqtUWDhF3IiKSuJs8EYQSFENDN1a7OEizcRnkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}