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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c66e52bba81401030aa04c0e08b9af9ad00e724f4f955c9e4ad29cdc1ab26475' 
  AND token = 'Ld5wPWl9r0XhN3IR0oZrd7Mz7aIbjXvnttPWDVWkHac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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