SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8b49928b8d0475974836e46239f3827750621293f49007bef454c639407dd7c' 
  AND token = '7PQRigwPXz7OumAHknFLYvt4gBK7EwZkSsoYhmqTmtk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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