SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3d771151df064d671dbd6cf255b5a13b23e4159da983b06c7c61b5a93f86ab2' 
  AND token = 'ERrEv6+uhBRlwv+eVodca/1baKM2qWLqjJBHYBsChtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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