SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd768c88989b9df565f19586dcfaaeeca8499976618f5f7c15e9df2b1903a6b23' 
  AND token = 'gLKApf0vZ+5GVGPjh04r2sql62g+5I/dTrmttju3Pfo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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