SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7bf0ba6927e574be5a4816a804d9c703687aff08e71088d41763d616736f93c' 
  AND token = 'qLmBZ8wLwJAujCuvwTEAM7aZpJrbmmtRNJEdVgSeW08=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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