SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12de9ccd7389a34d40fbfb59e7f9e844a7be9a663bbe1563a65e19905bed12e7' 
  AND token = 'n0da2fd7PCNummKOK6GZd4BScl0Ux8IkQZFrKtF9BwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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