SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df7252e9bdab424f8103c352d6d303812168dd876342cef339c2d6e6ac246f71' 
  AND token = 'rc7H8DXitHStyHYUleY/bYSIlizmxLscrNXICNKWgKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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