SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9769975ab1e5415088143c4faba241b38caebf8f59c78812e3af3cd94a2f5775' 
  AND token = 'FzsIJRPxLnFn3XMlglPaxmcb7pt9w0CumYLjkeLwyj8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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