SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87baa71099442f185a0f92740374a6f098f171a63e5033dc5e3f35fc942c9898' 
  AND token = 'MfD5Y9v+zkyqxmvg6g0yKOVBZvWrt2bbRvmD/Z9IMRY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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