SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8cf81b6b8b25429543bef4f600f53eb9bede685311ab4f0955b19911e672b35b' 
  AND token = 'vvBUWvm3I2CNEq8B2odeyKlRImDKrUF8CcIJUYvEiSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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