SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cac5f5aaaf5220ec130ff98ce497a75bfab0ccd96ae2e89c6359ddfcb2df8e3' 
  AND token = 'pn8B5SMNonQPTjaNWhfRtf+A8IlidFnApYoEj+SHuV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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