SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adb81da64de132e16e5794bbe3df492e58f6830f71ac636a1b93a0720af7818f' 
  AND token = 'SmbNfI9/KspRzFVMpBiPC4GYr/Yss/YX+qAdDqkOges=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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