SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e0d1f9db1b7cad246b5691ceb7edc8534616104d7cbf7f48b5d8853090eb577' 
  AND token = '7uSfgPsYRv/5+gpy4RWTOQ7ic4+OYtS5msNKjM/FLSk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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