SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '505d0c6871309e9c2a07a452cff95366fb6fdaff68a6829fd2bdc3f9d33344f9' 
  AND token = 'KPELCs5vPvuWuZC/BGYm8HbkHDJbeTx/JSdXlRUr0Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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