SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3fd739321f64578dd4a528276492e88e4478a9f784bf27f87c52454608b1f5' 
  AND token = 'zmRdisuV/51L0z5HkFpibiy9CZvghUwn6AaPHIMuuWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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