SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34703460a390477fe0155126e676cf9516efacab58d2d0462b4d6330373ef52a' 
  AND token = 'jFy6WrxuxF/oKYqQJgK44OF9MOPbBFQqBldeNTHCnWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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