SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b9c9af51336c72d17e9035778653a4a256b2b8f9261c7a13060a8ce62aad11c' 
  AND token = 'FqVNGRLhD6uYoyEkUSND1jaAmcET6tyTV9naCA7fsAo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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