SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5b0f6da94989622a784e204b6d5c2764ffa89de8971ef21181252387428cb54' 
  AND token = 'l23C5WKhld+tsGnCKYGjn3jY2IkC4Fpm1mjoHDszV5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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