SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16cf0be6f257404602986d83c3f78d171667635cba87677cfefcc3edc8590629' 
  AND token = 'LPPbWPdz9ZFK3yLbiRkexgtnyUJhHMCCgLCcwjJ5qOw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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