SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1619a8e514b136c9b8a534736376c468cd529e7d58253f1c4cbfe443892b19e' 
  AND token = 'j0gdmsapX8fP7w//tvJb+fHbig4tSFKsIDXYjB3K6PQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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