SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff2fad0715cbc89e68ccee5079529f706c6427161d5c60d060e898ae2aaf59f6' 
  AND token = 'mk70DxKsJAcLoFM7pfdSAnxGFSCATkwpvbGBmxcnNwA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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