SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45b58438a5e65f0ca5e8462c74f278ae5a0b4704cbf09798d93da60e9c51db71' 
  AND token = '6XNFX1ziEpIAJxhVADzXkqRdfH8OnwddF0WZQebJpec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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