SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8215e057ecf3110c46134f0a957caa51891ad95c497300cd66bf5242f71b2735' 
  AND token = 'NB2B8VjJxnUTc5Yt0dRvl8UjFhdwfetPdghHl+Twrg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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