SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '479bee4cea417acc930b231ad07f965c5e06e57681976861857f1eac8340263b' 
  AND token = 'kx0ppj3nTKUAhTnOyWr7sUokhajL+obdORj00mWIxNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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