SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42053656235ceab4516a542ab940109efcd473ea0d5377254571b247cc19e6cf' 
  AND token = 'N4OTEwyFA/+VHj4ngIxLv/Wg0uuDOy4tkHOrwD/27Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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