SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7826af7011bdaed4d4ffb8d055d5954fdf3aad29438eec6ce42d8a912d1fd2bf' 
  AND token = 'mZjKxlKaV/aos30VsiZh9GOs9qiwSsTSSJKGTguz/ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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