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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51c3d390e1694cf8695777635792dd731625a533d1ce361e34b60edd3c90506d' 
  AND token = 'RVkFrWzAzCwessqaEuOYOkB97oe/APzCaz2A4OLyOH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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