SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '873637d690ca62526662e6e294d8a93a91b4217cc895d92798e0913b125cae7f' 
  AND token = 'iAYSL2WiUDgXK+Jm0sKZfMYRB1N+L0Ddyss9z8xHEjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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