SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf8c55beab552f33308ac9fd5c654b0847b43628cbe9d3a737a8eedb951bab91' 
  AND token = 'QIG3LBWe7hZRW4BAl/1ngg277Hr5ZS0OlumvP36dZh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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