SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '494737ba44a1dc2d50776966204b442f74237067902ddbca123a7c6cb6dc13c9' 
  AND token = 'GqqGHueNyJfPvnMn6wNbjfPe7/omgzEvf3NmyINbfyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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