SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a8cd729d2faec0505bc05e76c9dc6af1cbc75383771abb6708aadcfb8043098' 
  AND token = 'wfKJ3qy8Ahv9tYkdY9LsqRV/+Kjxc4Ghy2iZjuJNluA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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