SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91da70690da5b1b31a9db5a5d92210278c29a2834c8157e024cb6404111adc0b' 
  AND token = 'nIGxTwlaoP+sl15FSqGMk+KsiEyGSlilljcVbdGKd+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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