SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a128f62c74b40f590fdf553b4350036cab8872f6d257607732319027baa1f9ec' 
  AND token = 'DmFIuKzudygHHmCEnJwnK4pehkXc13jlp5OLrMC1leQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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