SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0159b2a0bac53b0a3b76e7bd9add2e512c58739399ea62861e7710c91c7e4c0c' 
  AND token = 'hB4hfQ8+a5SYpeYXvJVdFlwRhnxPU3jDicmXqAMvEMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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