SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cac31701f997577b83397f10fb3f500299e741f48fdc55970cafba3ffb552a87' 
  AND token = 'xghe+Jq4lgiOBTeLtIdVU+vfNTI0Nzsofj/zDcU0Sgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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