SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39c383289b65143fd4b3aa4f003dfbcf3a1143985efbb0f4a3b89ecb6c2c9fb4' 
  AND token = 'CYmhFLbKnX7su8aTkYBehCIOtAgzH3XO/+OsYDlFp40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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