SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6735c7fae3230b2cbbed64354d38c69e2bdf8816a9251b0b9bfdaf48568bdf7a' 
  AND token = 'BifPTgjE4dh5+lMMF6vpFHfmkAO8knNGgTVOaNhZ8bI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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