SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '89c308ed35afdaf9c12dad9d23f749a9698c347f036482b45349d1e948385a50' 
  AND token = 'e6sfJIyEYhmQ42aaZSGoR2qAfEEJlXV4blwqhM9n+xM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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