SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e688a23a18c689b10afb796878b502a451d8a0f3545a543ff58ef77a202817ce' 
  AND token = 'MmfdVpNLWT71AaVS+iIWYVhwo5YTBfXigfUOQp1/eZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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