SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c705aea698f1c9cfc27d360fd9e44e27a08757c36dcb13fc0d422d904ae2682' 
  AND token = 'URumpM88goWcB5ljsKd1pmmphUGS15v9ynNnVIBGJIs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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