SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '990d317056574706219f1077ddd4492e5d45cdad123f0d0fa857836219baaf3c' 
  AND token = 'mwrlE5xHJOCbuHESKBlKla1IwW/EUtzZBhdJN7TQtws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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