SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2504ad07e56c39aa376025322966f9ad4870976b216634e0e33248015747615' 
  AND token = 'lVeVqiYoMfzNbRtTbueyxMH05wfxTs1PU6azUglBdyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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