SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87c692bbc885a8334e15b015adc6e8686711834ac8c653dc25827e9deb98a774' 
  AND token = 'hclAj7pGWYWFXg/YNaobWmpI+EM8iKdrKrwo6kSq7GU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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