SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b94058c3a292cd49888bcc337a1f233ad4d1974de661fd6e43bc2f0af363770c' 
  AND token = 'xQPZnb+XMbTXHWAYqE6dkcNkuTyT5xOyi8UD76CTqxA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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