SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8420b1984b57e3b4f8bf56bacbcc43a158e5da975f2b4a50b4192b8f926fa28' 
  AND token = 'iIDbtW6UZT5WiQHrthN95tvhEhsxTIDuFZOuezmHv3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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