SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0043e09207baa5b0f4eec08cba587ea4b0499aecb55588db7090661c2ee43d6' 
  AND token = 'T6GJV2qI5KHTRSescR6aVnIi3luVv9cItZV4SHuG8ks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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