SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6c204c5fad01a777b473100e93934c999d500037fbb50816034bbf514128f6d' 
  AND token = 'q6wOsl9w62UyneD6vLYz8pO9QVo++prqxNLNsQhAeLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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