SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b04c0edc8c3b2226ae37c740523dea77666fbe4559922364397ba401a9444f3f' 
  AND token = '/hv/B3pJcsmUr29yUAH69Mq+NJHVxyOkhUHorPdjZ88=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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