SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0c9df3b78f28baed9c526d1645f5c29e9c34af218957fa5abeba10af6de74403' 
  AND token = 'QSK4GQmH6YhvT5JGfjAj7va/KanATRS+JuCeI0IVc40=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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