SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b8f7caa675ddf8db7a1f9e474174f6e3c1c457b2d25a546a813d4f034a0fa5d' 
  AND token = '7ANjL8C6+vo2Thw6jlCOmd4l+IBKcYBuT6tzOySqhJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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