SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '917882d236708517a530675c5d7293bd98d0a92eb5d344ea65c0b14d731fe528' 
  AND token = 'xV+u3cIZitMa8Fvn5FaVdzlL1sfZH2u1/NKi7v6Wcn8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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