SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f66b1dd50130931477d81d162e0c3d1ff7f74687355f31a0be3e7ce2318161b' 
  AND token = 'HFjqGU0hVsIUFloOm0aFDGMuOcIE+vFOepG11p16ilw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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