SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c28a83f71a263eed0b3f89170972b08ad11c68a5d8f12a425409d3da196a9731' 
  AND token = 'IBd8UhQuHzgv25XABfYYF0//+XlzDAymln6DISiRAKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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