SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ac6cd0cbf2f94159276aacedf835cb603808c0ee679b575436c18f5b531d244' 
  AND token = 'qg1TkXHRENpp7Na1kW5NoLgDxCGXJJsPUgHGXbLlNG4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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