SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8f33346dde748032ef7a9e01996e27980559fc77c446d529c8359f518566511' 
  AND token = 'ZJg/+rPrOpkjERxnDGYgizUJj/HB3BI3aJlWRwXyCK0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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