SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e197f138bb2e6761c57a27490ea97899eb091ee58839c78721a614a945b97f36' 
  AND token = 'OkUNvgNgDnC8JlqrWzKcOdnmzBIBtbfmugGau32FEoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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