SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b43ec74e624b5d98f1165c371c5ed4166c3d380c2649360acee79182b19c52a' 
  AND token = 'FXGwIfFMV2TgT/4arIQxfziDvKUZSDw+DNitzgyafbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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