SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b19b8bd796a2b2938c20dfe28f8894e3091631d59864ab5eb6e320e58d4a8966' 
  AND token = 'YsJBLEh7xRdzuNFjwX4MYTzYHZjcmV+4qn54HbxZ5JM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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