SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91bbe8e230dd2defb3a2685b9498aa2b5c99f5d64e43f5f11d9e8cb6e8760b94' 
  AND token = '6v8rs6vOQ7JXyC/fEmFbbhyhqcGIrPYJ3waiB1yV+og=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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