SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71cf3927aff9cbdbf006e725d41e91c25f4d328f8b24c46a51d5caad7b590bcc' 
  AND token = 'i+RAULwTxn5lDlf7ua/DdNAcLmBttE/65uqypsDpGc8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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