SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37902760ea44172b1207961fee33914c7415014cde9e560a6ece8e121ae54e46' 
  AND token = 'PYy6cNps4aRAErsmbhBtij7CONjZBXWHgbiErQ2JZJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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