SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f491ffb3b759b68f0f6eba5dd04c6b483fb658776c64d49a0ef72193479cf590' 
  AND token = 'rNNVqEww13uhavBM72VEVTW3aLxiWC0gM3+noXdKp7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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