SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b54902bae3715e4850efb63660b168ed85cafe6e5ca1ecc8f1947337f2b0a240' 
  AND token = '5xPzhiZnBr0FwKx/OSTJ5HYiJhMGXDTw5WOD/ZHkE+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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