SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6a82b31d295fe5ecc7c74bbf044562ca7e376aa884122a1fec1a0ac5de255c8' 
  AND token = 'UwfRvkBws//k2OB9e7ZtUUnCFWGzmuOgklaYH/6TgWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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