SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3aca0226e7e3dd195c85a9eec5f1f5b246cbda73d4dd24bd07f526fb1ab1a00' 
  AND token = '7mCKRwShunzHNx2WwTJkM1G46D/TBCq+8v95P7ANnkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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