SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '84a8ca8ffb6e3d717f66c2d694a298f97e859e2a33d38f20c315b78519b60081' 
  AND token = 'QkLmq63FeUAwhGrnEsNWQZfLADnUZdNQjdX/CNvKHsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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