SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6038c385a817a759c10fbf56f76ab76f71e37eeabb97058245689be098343604' 
  AND token = 'RpkevvpOrjw2932k+rxYZhCKUFcaGhayUl2G8yMLsm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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