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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7fbe4c2729458fcc6cc7580371ba323528d891d12fc47ee0d758fe5c2ca09f' 
  AND token = 'ZlHrIg7Fm67ZMgi9LVysZHtked+e7kdUeRE3H7sJhvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00008

JSON explain

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