SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '546a8a2559c83bf05ec4237fa1f9e2bb52d12891800758481aa1fdd522673140' 
  AND token = 'Po0owMCAFpzFsCY71oZoV7eGhJ7nSAoHysMsjmvYTQE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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