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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab8a277317f34b3f937cee9d3d83830e8944a175e03e1f50bcc4da704d310123' 
  AND token = 'a7LpjZTrBUwd2OH/gWuKOQZaR9hhkGrRIZtdEKZpQgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}