SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b57dd87ff43692cefd53ca5139a9d853909e3ecc9a9ade146d3daa785e0ca271' 
  AND token = 'HLQjyf2BipIiISgPoYouvI2nRr/TtcFaPJTecB1FlTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00076

JSON explain

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