SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ecead99c8bdb883b48c57d1a4659f1acb3a66d0effe4e15711abec2695d2580' 
  AND token = 'iz3TySIvjOZwgr3rpNZeycFrz788NMmCgHsr0bSWYDk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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