SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e7a005a890f532dbbe3c2a0a019bb1cfb934f9d1219b6603dbe5271c99c3c6e' 
  AND token = 'RzjLcOwiEkVEJEWZaz0YDZG8CLQgqvCEVoyzjhFEWfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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